Question

Which of the following descriptions of a Y-linked trait in humans is correct?

a. All the sons of an affected father will be affected with the trait.
b. Half the sons of a mother whose father was affected with the trait will be affected.
c. Half the sons of an affected father will not be affected with the trait and the other half will be infertile.
d. All the daughters of an affected father will be phenotypically normal themselves but half of their own sons will be affected with the trait.
e. The parents of an affected man likely were both phenotypically normal.

Answer 1

The correct description of a Y-linked trait is that all the sons of an affected father will be affected, because the Y chromosome is passed directly from father to son.

Step-by-step explanation:

The correct description of a Y-linked trait in humans is that all the sons of an affected father will be affected with the trait. This is because males only have one Y chromosome, and any gene that is situated on the Y chromosome will be expressed in males. The Y chromosome is inherited directly from father to son, meaning if the father has the Y-linked trait, each of his sons will inherit that same Y chromosome, and thus the trait.

For a Y-linked trait, statements about a mother passing on the trait or daughters inheriting the trait do not apply, as females do not possess a Y chromosome. Also, Y-linked traits do not typically result in carriers, as there is no second Y chromosome to mask the effect of a variant on the one Y chromosome a male has.

Therefore, the correct choice among the given options is (a) All the sons of an affected father will be affected with the trait.